Katharine McPhee feared an eating disorder 'relapse' in pregnancy. She's not alone.

Pregnancy can be challenging for many women as they watch their bodies change and grow. For women with a history of disordered eating, those challenges are sometimes amplified during those physically and emotionally-demanding months.

That was the case for Katharine McPhee Foster.

The actress, who recently welcomed a son with husband David Foster, appeared on Dr. Berlin's Informed Pregnancy Podcast on March 1, just days before her due date, and opened up about her relapse with food issues during pregnancy.

"The biggest challenge for me through the pregnancy was really the body issue stuff just suddenly came up in a way that hadn’t been present in a long time," she said.

McPhee, who was runner-up on the fifth season of "American Idol," has been candid in the past about her struggle with bulimia. Those with bulimia will go through periods of bingeing and purging and often maintain a consistent weight.

The 36-year-old's issues go back to middle school when she "started restricting food," she shared.

"You start itemizing foods, like you put food in categories like this is bad food, this is good food, this is a good day, this is a bad day. And the restricting turns into an obsession with the food."

Through a treatment program and therapy she committed to before "Idol," McPhee said that although she still has her ups and downs, she has "felt stable" for the last four to five years. She was shocked when thoughts of disordered eating started to seep back in during the first trimester of pregnancy.

"I was really ravenous the first trimester," she said. "The food hunger would come on so quickly and in your brain your like 'Is this the eating disorder version of me or is this actually my body?'"

She also struggled with a distortion of the way she looked, so she sought help from the same psychiatrist she worked with before "American Idol."

Her therapist told her that "it’s really common for women who have struggled with eating disorders in the past to have almost like a relapse in some sense when they enter pregnancy."

In the United States, 30 million people will be affected by an eating disorder at some point in their lives.

And there's a broad spectrum of disordered eating — which refers to a number of abnormal behaviors like calorie counting or a rigid exercise routine — but there are specific criteria for eating disorders, which are diagnosed mental illnesses. The big three are anorexia, bulimia and binge eating disorder.

Ilene Fishman, a board member of the National Eating Disorders Association and eating disorders clinician, said it makes sense that thoughts and feelings of disordered eating may resurface during pregnancy when one feels "out of control."

It can be especially scary for someone who may have resolved their eating disorder by feeling safe in their body, controlling their size, shape and weight, and also being able to manage their hunger and fullness, to lose some control of that, she said.

"Key to recovery from any eating disorder is trusting one’s body and trusting one’s hunger so it makes sense that during pregnancy that’s more confusing," she said.

Fishman said people who have struggled in the past are more likely to have eating disorder-related thoughts than they are to actually relapse.

"Eating disorders are basically self-destructive and they speak to a very unhealthy relationship with self," she said. "If psychotherapy is successful, people will have a healthy relationship with themselves, which then it would be unacceptable to hurt oneself in that way,"

That was the case for McPhee, who returned to therapy, was able to "weather" disordered eating thoughts throughout her pregnancy.

"I look in the mirror and I’m like, 'Ya my legs, my thighs, my arms are a little bit thicker,' but I’m OK with it. I’m really OK with it and I'm proud of myself," she said on the podcast.

Tips for dealing with disordered eating thoughts during pregnancy

McPhee did the right thing by seeking help when thoughts of disordered eating returned during her pregnancy. Fishman offered these suggestions:

Seek professional help sooner rather than later: "Going back to a treatment professional from the past makes sense," she said, but it could also be an opportunity to have an experience with a new professional. Either way, reach out to someone.

See it as an opportunity for deeper growth: "We live in a society where we get challenged all the time and when we age, our bodies change, so if we don’t have a good handle on this stuff, we're gonna get tossed around," she said. Overcoming recurrent thoughts of disordered eating can lead to a more successful recovery and even more resilience.

If you or someone you know is struggling with body image or eating concerns, the National Eating Disorders Association's toll-free and confidential helpline is available by phone or text at 1-800-931-2237 or by click-to-chat message at nationaleatingdisorders.org/helpline. For 24/7 crisis situations, text "NEDA" to 741-741.

This article originally appeared on USA TODAY: Katharine McPhee worried about eating disorder 'relapse' in pregnancy